1. Field of the Invention
The present invention generally relates to de-interlacing, and more particularly to de-interlacing using remote interpolation.
2. Description of the Prior Art
Most broadcasting television signals, such as NTSC, PAL or SECOM, are interlaced to display odd-field and even-field in turn, which are perceived as a whole frame due to persistence of vision. Interlaced video signals could be satisfactorily broadcast without consuming much bandwidth, but disadvantageously have reduced vertical resolution, line or area flicker. The video signals for computer displays, on the other hand, are non-interlaced or progressive to directly display the whole frame on the display.
In order to display the interlaced video signals on a progressive-type display, such as a computer display, the interlaced video signals should be transformed into non-interlaced or progressive video signals through a de-interlacing or line doubling process. Through the de-interlacing, the original odd-field and even-field are combined into a frame.
Video signals are conventionally de-interlaced through spatial, temporal, or spatial-temporal transformation. In the spatial transformation (also known as intra-field transformation), pixel/sample or pixels/samples in the same field are used to generate or insert new pixel. In the temporal transformation (also known as inter-field transformation), pixels in neighboring fields respectively are used to generate new pixel. In the spatial-temporal transformation, the spatial and the temporal transformations are collectively used to generate new pixel.
Among the various transformations mentioned above, the spatial transformation is a basic and important one, in particularly when scene change exists or the temporal transformation is unsatisfactory. One of the fundamental principles of the spatial transformation is to interpolate a new pixel from neighboring pixel or pixels based on the correlation relationship among the new pixel to be interpolated and the neighboring pixels.
FIG. 1A and FIG. 1B illustrate a conventional interpolation in which line n−1 and line n+1 are neighboring lines of a field, and line n is a new line to be interpolated from the line n−1 and the line n+1. Specifically, in FIG. 1A, a new pixel X is interpolated from neighboring pixels of columns k−1, k, and k+1, as being illustratively shaded. In FIG. 1B, another new pixel X+1 is interpolated from neighboring pixels of columns k, k+1, and k+2, as being illustratively shaded.
The conventional interpolation discussed above disadvantageously results in serrate or blurred line, particularly along an edge. Accordingly, a need has arisen to propose a novel transformation or interpolation to procure smooth line in the de-interlacing.